1. Field of the Invention
The present invention relates to a silent electromagnetic relay and particularly to a silent electromagnetic relay which generates no offensive collision noise at times of operation and return.
2. Description of the Related Art
As a conventional silent electromagnetic relay, there is a silencing device of a small relay as shown in FIG. 1 of Japanese Patent Application Laid-open No. 8-69737, for example, in which an elastic member 31 bent substantially in a V shape is mounted in a position of an L-shaped armature 27 and facing a magnetic pole portion of a core 29 and an elastic member 32 is mounted in a position of the armature 27 and facing an outward face of the yoke 23, the armature 27 supported for turning on an upper end portion of a yoke 23. The elastic member 31 comes in contact with the core 29 at the time of operation and the elastic member 32 comes in contact with the yoke 23 at the time of return and, as a result, the elastic members 31, 32 absorb the collision noise.
However, in the above-described small relay, it is necessary to change a bending angle of the armature according to a change to the specification made by a customer, e.g., a change to an operating voltage, a return voltage, or the like in the above-described small relay, though the basic structure is the same. In this case, in general, in order to eliminate the necessity to start over designing related to operations of the core and the armature, the bending angle of the armature is changed while keeping a distance between the magnetic pole portion of the core and a contact face of the armature constant and therefore a distance between the outward face of the yoke and the contact face of the armature changes. Consequently, in order to maintain a predetermined degree of silencing effect at the time of return, it is necessary to change a shape of the elastic member that comes in contact with the outward face of the yoke. As a result, a silent spring adapted to a customer specification need be prepared, which complicates parts control and increases cost of manufacturing.
Moreover, in the above-described small relay, a metal armature comes in contact with a metal core or a metal yoke both at the time of operation and at the time of return and therefore it is not easy to obtain high silencing effect.
In view of the above problems, it is an object of the present invention to provide a silent electromagnetic relay in which a predetermined degree of silencing effect can be maintained irrespective of a change to the specification, a higher silencing effect can be obtained at the time of return, the parts control is easy, and the cost of manufacturing is low.